import java.util.ArrayList;
import java.util.List;

/**
* Created with IntelliJ IDEA.
* Description:
* User:DELL
* Date:2025-04-17
* Time:23:59
*/
public class Test6 {
    int[] ret;
    int[] index;//标记nums中当前元素的原始下标
    int[] tmpNums;
    int[] tmpIndex;
    public List<Integer> countSmaller(int[] nums) {
        int n=nums.length;
        ret=new int[n];
        index=new int[n];
        tmpNums=new int[n];
        tmpIndex=new int[n];
        //初始化下标
        for(int i=0;i<n;i++){
            index[i]=i;
        }
        mergeSort(nums,0,n-1);
        List<Integer> l=new ArrayList<Integer>();
        for(int x:ret){
            l.add(x);
        }
        return l;
    }
    public void mergeSort(int[] nums,int left,int right){
        if(left>=right){
            return;
        }
        //根据中间元素划分区间
        int mid=(left+right)/2;
        //[left,mid] [mid+1,right]
        //处理左右两个区间
        mergeSort(nums,left,mid);
        mergeSort(nums,mid+1,right);
        //处理一左一右
        int cur1=left,cur2=mid+1,i=0;//降序排序
        while(cur1<=mid&&cur2<=right){
            if(nums[cur1]<=nums[cur2]){
                tmpNums[i]=nums[cur2];
                tmpIndex[i++]=index[cur2++];
            }else{
                ret[index[cur1]]+=right-cur2+1;
                tmpNums[i]=nums[cur1];
                tmpIndex[i++]=index[cur1++];
            }
        }
        //处理排序
        while(cur1<=mid){
            tmpNums[i]=nums[cur1];
            tmpIndex[i++]=index[cur1++];
        }
        while(cur2<=right){
            tmpNums[i]=nums[cur2];
            tmpIndex[i++]=index[cur2++];
        }
        for(int j=left;j<=right;j++){
            nums[j]=tmpNums[j-left];
            index[j]=tmpIndex[j-left];
        }
    }
}
